Here comes the sun

By John Loos

September 2009- Solar power isn't just for watches and pocket calculators. Plants around the globe have turned the sun's rays into countless megawatts of electricity, taking advantage of a boundlessly renewable natural resource most of us simply see as daylight.

According to the Solar Energy Industries Association, Washington, D.C., aside from everyday uses such as the lighting or heating of a building, the sun's power can be harnessed through photovoltaics, which converts light into electricity. There's also a process known as concentrating solar power, in which a reflector and a receiver work in tandem to absorb reflected and refocused solar radiation. And according to the U.S Department of Energy, the United States produced 72.87 quadrillion BTUs of solar energy in 2007, although that figure remains less than 2 percent of the country's total energy output.

Helping boost that figure is the Martin Next Generation Solar Energy Center, Indiantown, Fla., which will come online in 2010 and will be the world's first hybrid solar facility connected to an existing combined-cycle power plant. It will produce 75 megawatts of electricity annually through the use of more than 180,000 curved mirrors to track the sun.

Constructing this sizable project, however, takes an enormous amount of aluminum, which Norsk Hydro ASA, Oslo, Norway--specifically produced at its Hydro Extrusions Americas unit--is more than happy to supply.

Using aluminumHydro is providing the Martin facility with frames, supports, legs and connectors to lift the 180,000 curved mirrors and enable them to move with the sun. However, to harness the Sunshine State's bountiful solar potential, the facility needed to be built tough enough to handle Florida's other infamous weather phenomenon: hurricanes. Hydro's extruded aluminum frames are designed to be lightweight and durable, with enough torsional strength to resist the immense winds generated by a gulf storm.

This type of project is nothing new for Hydro. Supplying renewable energy projects with aluminum is a prominent part of its business. In fact, its aluminum frames are being used at facilities that, combined, generate nearly 300 megawatts of electricity.

"Hydro Aluminum has a long history with renewable energy," says Allan Bennett, vice president of solar market development for Hydro. "The company name comes from the hydro-electric power we have been using [and are still using] for nearly 100 years. Hydro is already present in the solar industry through its joint ventures in thin-film photovoltaics, ingots and wafers, and a poly-silicon plant. Also, Hydro's Building Systems division is on the leading edge of building-integrated solar applications. Expanding our presence by supplying extruded aluminum to the CSP utility-scale solar projects makes good sense. Our Extrusion Americas division has already done four CSP plants."

The company is currently working on its fifth project.

In a white paper regarding aluminum's advantage in CSP applications, Hydro highlights the metal's stiffness, mobility, weight, strength, modularity and ease of fabrication as factors that make it ideal for building support structures for solar plants.

"There's quite a bit that we feel is special about our extrusions," says Bennett. "These designs provide the strength needed to withstand environmental wear and tear, but they're easier and quicker to install than steel structures. That means less equipment and fewer man-hours to get the solar field built, which reduces cost."

But what really stands out about Hydro's aluminum extrusions, in Bennett's mind, is their sustainability.

"They have around 75 percent post-industrial recycled content in them, with no degradation of mechanical properties," he says. "In addition, that recycled content gives the production of the extrusions a smaller carbon footprint than competing materials."

For Hydro, combining an environmentally conscious metal with clean energy applications is a smart pairing. And, just as with increasing popular solar energy solutions, it looks like Hydro's aluminum extrusions will continue to benefit from sunny days ahead. MM